diff --git a/lucene/analysis/kuromoji/src/java/org/apache/lucene/analysis/ja/util/BinaryDictionaryWriter.java b/lucene/analysis/kuromoji/src/java/org/apache/lucene/analysis/ja/util/BinaryDictionaryWriter.java
index 1aec333aabc..2cd4cca3031 100644
--- a/lucene/analysis/kuromoji/src/java/org/apache/lucene/analysis/ja/util/BinaryDictionaryWriter.java
+++ b/lucene/analysis/kuromoji/src/java/org/apache/lucene/analysis/ja/util/BinaryDictionaryWriter.java
@@ -34,7 +34,7 @@ import org.apache.lucene.util.ArrayUtil;
 
 import org.apache.lucene.analysis.ja.dict.BinaryDictionary;
 
-public abstract class BinaryDictionaryWriter {
+abstract class BinaryDictionaryWriter {
   private final static int ID_LIMIT = 8192;
 
   private final Class<? extends BinaryDictionary> implClazz;
diff --git a/lucene/analysis/kuromoji/src/java/org/apache/lucene/analysis/ja/util/CharacterDefinitionWriter.java b/lucene/analysis/kuromoji/src/java/org/apache/lucene/analysis/ja/util/CharacterDefinitionWriter.java
index 60edabed0d9..cf5a8311a95 100644
--- a/lucene/analysis/kuromoji/src/java/org/apache/lucene/analysis/ja/util/CharacterDefinitionWriter.java
+++ b/lucene/analysis/kuromoji/src/java/org/apache/lucene/analysis/ja/util/CharacterDefinitionWriter.java
@@ -30,7 +30,7 @@ import org.apache.lucene.codecs.CodecUtil;
 import org.apache.lucene.store.DataOutput;
 import org.apache.lucene.store.OutputStreamDataOutput;
 
-public final class CharacterDefinitionWriter {
+final class CharacterDefinitionWriter {
 
   private final byte[] characterCategoryMap = new byte[0x10000];
   
diff --git a/lucene/analysis/kuromoji/src/java/org/apache/lucene/analysis/ja/util/ConnectionCostsBuilder.java b/lucene/analysis/kuromoji/src/java/org/apache/lucene/analysis/ja/util/ConnectionCostsBuilder.java
index d1bc8467110..38063c34954 100644
--- a/lucene/analysis/kuromoji/src/java/org/apache/lucene/analysis/ja/util/ConnectionCostsBuilder.java
+++ b/lucene/analysis/kuromoji/src/java/org/apache/lucene/analysis/ja/util/ConnectionCostsBuilder.java
@@ -24,7 +24,7 @@ import java.nio.charset.StandardCharsets;
 import java.nio.file.Files;
 import java.nio.file.Path;
 
-public class ConnectionCostsBuilder {
+class ConnectionCostsBuilder {
 
   private ConnectionCostsBuilder() {
   }
diff --git a/lucene/analysis/kuromoji/src/java/org/apache/lucene/analysis/ja/util/ConnectionCostsWriter.java b/lucene/analysis/kuromoji/src/java/org/apache/lucene/analysis/ja/util/ConnectionCostsWriter.java
index a629fffa3b4..746a4f74144 100644
--- a/lucene/analysis/kuromoji/src/java/org/apache/lucene/analysis/ja/util/ConnectionCostsWriter.java
+++ b/lucene/analysis/kuromoji/src/java/org/apache/lucene/analysis/ja/util/ConnectionCostsWriter.java
@@ -29,7 +29,7 @@ import org.apache.lucene.codecs.CodecUtil;
 import org.apache.lucene.store.DataOutput;
 import org.apache.lucene.store.OutputStreamDataOutput;
 
-public final class ConnectionCostsWriter {
+final class ConnectionCostsWriter {
   
   private final short[][] costs; // array is backward IDs first since get is called using the same backward ID consecutively. maybe doesn't matter.
   private final int forwardSize;
diff --git a/lucene/analysis/kuromoji/src/java/org/apache/lucene/analysis/ja/util/DictionaryBuilder.java b/lucene/analysis/kuromoji/src/java/org/apache/lucene/analysis/ja/util/DictionaryBuilder.java
index bdf83683ea4..373ce0970db 100644
--- a/lucene/analysis/kuromoji/src/java/org/apache/lucene/analysis/ja/util/DictionaryBuilder.java
+++ b/lucene/analysis/kuromoji/src/java/org/apache/lucene/analysis/ja/util/DictionaryBuilder.java
@@ -20,10 +20,20 @@ package org.apache.lucene.analysis.ja.util;
 import java.io.IOException;
 import java.nio.file.Path;
 import java.nio.file.Paths;
+import java.util.Locale;
 
+/**
+ * Tool to build dictionaries.
+ */
 public class DictionaryBuilder {
 
-  public enum DictionaryFormat { IPADIC, UNIDIC }
+  /** Format of the dictionary. */
+  public enum DictionaryFormat {
+    /** IPADIC format */
+    IPADIC,
+    /** UNIDIC format */
+    UNIDIC
+  }
 
   private DictionaryBuilder() {
   }
@@ -42,7 +52,7 @@ public class DictionaryBuilder {
   }
 
   public static void main(String[] args) throws IOException {
-    DictionaryFormat format = DictionaryFormat.valueOf(args[0].toUpperCase());
+    DictionaryFormat format = DictionaryFormat.valueOf(args[0].toUpperCase(Locale.ROOT));
     String inputDirName = args[1];
     String outputDirName = args[2];
     String inputEncoding = args[3];
diff --git a/lucene/analysis/kuromoji/src/java/org/apache/lucene/analysis/ja/util/TokenInfoDictionaryBuilder.java b/lucene/analysis/kuromoji/src/java/org/apache/lucene/analysis/ja/util/TokenInfoDictionaryBuilder.java
index bbed37b0692..3274fefb15f 100644
--- a/lucene/analysis/kuromoji/src/java/org/apache/lucene/analysis/ja/util/TokenInfoDictionaryBuilder.java
+++ b/lucene/analysis/kuromoji/src/java/org/apache/lucene/analysis/ja/util/TokenInfoDictionaryBuilder.java
@@ -37,7 +37,7 @@ import org.apache.lucene.util.fst.PositiveIntOutputs;
 
 /**
  */
-public class TokenInfoDictionaryBuilder {
+class TokenInfoDictionaryBuilder {
 
   private final String encoding;
   private final Normalizer.Form normalForm;
diff --git a/lucene/analysis/kuromoji/src/java/org/apache/lucene/analysis/ja/util/TokenInfoDictionaryWriter.java b/lucene/analysis/kuromoji/src/java/org/apache/lucene/analysis/ja/util/TokenInfoDictionaryWriter.java
index 81cad4f8aba..8487bd725cc 100644
--- a/lucene/analysis/kuromoji/src/java/org/apache/lucene/analysis/ja/util/TokenInfoDictionaryWriter.java
+++ b/lucene/analysis/kuromoji/src/java/org/apache/lucene/analysis/ja/util/TokenInfoDictionaryWriter.java
@@ -25,7 +25,7 @@ import java.util.Objects;
 import org.apache.lucene.analysis.ja.dict.TokenInfoDictionary;
 import org.apache.lucene.util.fst.FST;
 
-public class TokenInfoDictionaryWriter extends BinaryDictionaryWriter {
+class TokenInfoDictionaryWriter extends BinaryDictionaryWriter {
   private FST<Long> fst;
 
   TokenInfoDictionaryWriter(int size) {
diff --git a/lucene/analysis/kuromoji/src/java/org/apache/lucene/analysis/ja/util/UnknownDictionaryBuilder.java b/lucene/analysis/kuromoji/src/java/org/apache/lucene/analysis/ja/util/UnknownDictionaryBuilder.java
index c3abd456038..4316add3a6c 100644
--- a/lucene/analysis/kuromoji/src/java/org/apache/lucene/analysis/ja/util/UnknownDictionaryBuilder.java
+++ b/lucene/analysis/kuromoji/src/java/org/apache/lucene/analysis/ja/util/UnknownDictionaryBuilder.java
@@ -29,7 +29,7 @@ import java.util.List;
 
 import org.apache.lucene.analysis.ja.dict.CharacterDefinition;
 
-public class UnknownDictionaryBuilder {
+class UnknownDictionaryBuilder {
   private static final String NGRAM_DICTIONARY_ENTRY = "NGRAM,5,5,-32768,記号,一般,*,*,*,*,*,*,*";
 
   private final String encoding;
diff --git a/lucene/analysis/kuromoji/src/java/org/apache/lucene/analysis/ja/util/UnknownDictionaryWriter.java b/lucene/analysis/kuromoji/src/java/org/apache/lucene/analysis/ja/util/UnknownDictionaryWriter.java
index 6809825629d..1144d23f483 100644
--- a/lucene/analysis/kuromoji/src/java/org/apache/lucene/analysis/ja/util/UnknownDictionaryWriter.java
+++ b/lucene/analysis/kuromoji/src/java/org/apache/lucene/analysis/ja/util/UnknownDictionaryWriter.java
@@ -19,12 +19,11 @@ package org.apache.lucene.analysis.ja.util;
 
 import java.io.IOException;
 import java.nio.file.Path;
-import java.nio.file.Paths;
 
 import org.apache.lucene.analysis.ja.dict.CharacterDefinition;
 import org.apache.lucene.analysis.ja.dict.UnknownDictionary;
 
-public class UnknownDictionaryWriter extends BinaryDictionaryWriter {
+class UnknownDictionaryWriter extends BinaryDictionaryWriter {
   private final CharacterDefinitionWriter characterDefinition = new CharacterDefinitionWriter();
   
   public UnknownDictionaryWriter(int size) {
diff --git a/lucene/analysis/kuromoji/src/test/org/apache/lucene/analysis/ja/dict/TokenInfoDictionaryTest.java b/lucene/analysis/kuromoji/src/test/org/apache/lucene/analysis/ja/dict/TokenInfoDictionaryTest.java
index 69328d85813..4b9d6bd8622 100644
--- a/lucene/analysis/kuromoji/src/test/org/apache/lucene/analysis/ja/dict/TokenInfoDictionaryTest.java
+++ b/lucene/analysis/kuromoji/src/test/org/apache/lucene/analysis/ja/dict/TokenInfoDictionaryTest.java
@@ -23,10 +23,9 @@ import java.nio.charset.StandardCharsets;
 import java.nio.file.Files;
 import java.nio.file.Path;
 
+import org.apache.lucene.analysis.ja.util.DictionaryBuilder;
 import org.apache.lucene.analysis.ja.util.DictionaryBuilder.DictionaryFormat;
 import org.apache.lucene.analysis.ja.util.ToStringUtil;
-import org.apache.lucene.analysis.ja.util.TokenInfoDictionaryBuilder;
-import org.apache.lucene.analysis.ja.util.TokenInfoDictionaryWriter;
 import org.apache.lucene.util.IntsRef;
 import org.apache.lucene.util.IntsRefBuilder;
 import org.apache.lucene.util.LuceneTestCase;
@@ -68,9 +67,13 @@ public class TokenInfoDictionaryTest extends LuceneTestCase {
         printer.println(entry);
       }
     }
-    TokenInfoDictionaryBuilder builder = new TokenInfoDictionaryBuilder(DictionaryFormat.IPADIC, "utf-8", true);
-    TokenInfoDictionaryWriter writer = builder.build(dir);
-    writer.write(dir);
+    Files.createFile(dir.resolve("unk.def"));
+    Files.createFile(dir.resolve("char.def"));
+    try (OutputStream out = Files.newOutputStream(dir.resolve("matrix.def"));
+        PrintWriter printer = new PrintWriter(new OutputStreamWriter(out, StandardCharsets.UTF_8))) {
+      printer.println("1 1");
+    }
+    DictionaryBuilder.build(DictionaryFormat.IPADIC, dir, dir, "utf-8", true);
     String dictionaryPath = TokenInfoDictionary.class.getName().replace('.', '/');
     // We must also load the other files (in BinaryDictionary) from the correct path
     return new TokenInfoDictionary(ResourceScheme.FILE, dir.resolve(dictionaryPath).toString());
diff --git a/lucene/analysis/kuromoji/src/test/org/apache/lucene/analysis/ja/dict/UnknownDictionaryTest.java b/lucene/analysis/kuromoji/src/test/org/apache/lucene/analysis/ja/util/UnknownDictionaryTest.java
similarity index 93%
rename from lucene/analysis/kuromoji/src/test/org/apache/lucene/analysis/ja/dict/UnknownDictionaryTest.java
rename to lucene/analysis/kuromoji/src/test/org/apache/lucene/analysis/ja/util/UnknownDictionaryTest.java
index 6330f41cea8..9a0fbc9e76e 100644
--- a/lucene/analysis/kuromoji/src/test/org/apache/lucene/analysis/ja/dict/UnknownDictionaryTest.java
+++ b/lucene/analysis/kuromoji/src/test/org/apache/lucene/analysis/ja/util/UnknownDictionaryTest.java
@@ -14,11 +14,8 @@
  * See the License for the specific language governing permissions and
  * limitations under the License.
  */
-package org.apache.lucene.analysis.ja.dict;
+package org.apache.lucene.analysis.ja.util;
 
-
-import org.apache.lucene.analysis.ja.util.CSVUtil;
-import org.apache.lucene.analysis.ja.util.UnknownDictionaryWriter;
 import org.apache.lucene.util.LuceneTestCase;
 import org.junit.Test;